The present invention relates to a seek operation control apparatus and, more particularly, to an apparatus for accurately controlling and driving a magnetic head at high speed when a seek instruction is input to a magnetic disk system.
A typical conventional magnetic head position control scheme is based on servo data pre-recorded on a magnetic disk in a magnetic disk system. In such a magnetic disk system, in order to move a magnetic head to a track position designated by an input seek instruction, head position control is classified into speed control, transition control, and positioning control.
Speed control is control for driving a carriage to move the magnetic head to a track position designated by the seek instruction. Transition control is intermediate control between speed control and positioning control so as to stop the magnetic head at the designated track position. Positioning control is control for holding the magnetic head at the designated track position. Positioning control is normally performed using a position signal having a predetermined waveform at the designated track position.
When a pulse signal including the number of pulses corresponding to the number of tracks for the magnetic head to be moved is supplied as a seek instruction in an interface between a magnetic disk controller and the seek operation control apparatus, if the magnetic head is moved after the pulse signal is completely received, a predetermined position signal used in positioning control can be selected. However, this results in a lengthy seek operation since the magnetic head is not allowed to begin moving until the pulse signal is completely received.